The present disclosure relates to electrostatographic printing and/or xerography systems. Specifically this disclosure relates to in-situ machine measurement of photoreceptor charging uniformity in marking engines within xerographic systems.
In electrostatographic systems, a photoreceptor may be supported by a mechanical carrier, such as a drum or a belt. The photoreceptor may be charged to a generally uniform charge by subjecting the photoreceptor to a suitable charging device. The charge distribution on the photoreceptor may then be altered by the application of radiation, e.g., a laser, to the surface of the photoreceptor. The toner particles adhere electrostatically to the suitably charged portions of the photoreceptor. The toner particles may then be transferred, by the application of electric charge to a print sheet or intermediate belt, forming the desired image on the print sheet or intermediate belt. An electric charge may also be used to separate or “detack” the print sheet from the photoreceptor.
The charge uniformity of the photoreceptor bears a direct relationship on the quality of the work product of the xerographic system. Control systems for uniform charge distribution requires monitoring the charge disposed on the photoreceptor and has been made possible by advances in non-contacting electrostatic voltmeters (ESV's) which measure the surface voltage of the photoreceptor. Based upon micro-electro-mechanical (MEM) modulation technology, non-contacting ESV's have been reduced in size to be adaptable to the reduced footprint available on the surface of photoreceptors made smaller by the overall reduction in size of the xerographic system.
An exemplary method and apparatus for use in an ESV is discussed in U.S. Pat. No. 6,177,800 to Kubby et al. (“Kubby”), and is incorporated by reference in its entirety. Kubby discloses a MEM based ESV device that includes a sense probe assembly having a plurality of sense probes for measuring voltage by capacitive coupling.